Telephone system



A. BRANDSTETTER March 31, 1942.

TELEPHONE SYSTEM.

Filed Oct. 27, 1959 Qmm Inventor ALOIS BRANDSTETTER A ttorney- Patented Mar. 31, 1942 Ui'lED STTS TE OFFICE TELEPHONE SYSTEM poration of Germany Application October 2'7, 1939, Serial No. 301,657 In Germany October 2'7, 1938 9 Claims.

This invention relates to a circuit arrangement for signalling over junction lines in automatic telephone installations, wherein when a connection is set up from the one exchange to the prearranged exchange two or more signals are transmitted back in order to carry out certain switch operations.

Such switch operations may, for example, be used for automatically connecting or disconnecting (for example disconnection of a register) certain connecting devices in the prearranged exchange at a certain stage of a setting up of the connection or to give a signal to the operator regarding certain conditions of operation in the series exchange (for example the reply of the called subscriber).

The operation of the devices which carry out the transmission of the signals to the prearranged exchange is caused automatically under the control of switch operations effected, for example in the final selector, at a certain stage of the setting up of the connection, for example by the transmission of the disengaged signal and on the lifting of the receiver by the called subscriber. Now, it may happen that these two switch operations coincide or succeed each other so closely that the two devices actuated by them will likewise operate simultaneously and that therefore, as they both control the same source of current for the transmission of the signals to the prearranged exchange, only one signal arrives and only one switch operation is initiated in the prearranged exchange.

It is the object of this invention to avoid this defect. This is achieved by providing, at the incoming end of a junction line, two devices which when being actuated cause certain signals to be transmitted over the junction line back to the prearranged exchange in such a manner that even on a simultaneous actuation of both devices the signals eifected by them are sent out in succession.

An embodiment of the invention is hereafter described with reference to the accompanying drawing, only those parts which are necessary for the understanding of the invention being described and illustrated.

First of all the normal connection is described in which after the sending out of the disengaged signal the signal for the disconnection of the register and thereupon when the subscriber answers the call the reply signal is transmitted to the operator in the exchange A.

In the embodiment shown it is assumed, that a connection extending over the line VL from exchange A to exchange B has been established up to the final selector LW in exchange B and that the called subscriber has been found to be disengaged. In this case a speech-frequency source of current Which sends out the so-called disengaged signal, is automatically applied in the final selector to the line conductors a/ b by means which as such are known and which are therefore not shown. This disengaged signal causes the signal receiver SE which precedes the final selector to operate. Its relay F is momentarily energised, that is to say during the period of the disengaged signal transmission which is repeated until the call subscriber has answered the call, and closes at its contact if the circuit for the relay W. The circuit of relay W extends from earth at contact If, contact Zzl, its windings I and II, over resistance Wi to battery, earth. After energisation relay W operates its contacts. At contact 3w it closes the circuit for the relay T which extends from earth at the contact Ilic of the seizing relay C, not shown (contact lilo being closed when the final selector LW is seized) over the winding of relay T and the windings I and II of relay W, resistance wt, to battery, earth, and at the contacts 41.0 and 5w it applies the source of alternating current WQ to the conductors of the junction line VL. The 50-cycle alternating current transmitted from the source over the junction line VL to the exchange A causes the relay X, arranged at the outgoingend of the junction line VL in the exchange A and tuned to the period of the transmitted alternating current, to operate, whereby the desired switch operation in this case th disconnection of the register Rg associated with the exchange A, is now effected as follows: Relay X closes momentarily its contact lZx in the circuit of relay Y which extends from earth at the contact I50 of the seizing relay C, not shown (contact i'5c is closed when the junction line VB is seized), contact I200, winding of relay Y to battery, earth. Relay Y completes, over its contact 13y, a holding circuit as its energising circuit above described is severed at its contact [2:0 after the release of relay X. At the same time it opens its contact My in the circuit of the test relay P of selector AW which extends from earth at contact 150, contact l ly, winding of relay P, to battery, earth. The start selector AW of the register and, therefore, the register itself is re leased for further connections.

Meanwhile the relay T has operated in the exchange B over contact 310 and has connected. itself over its contact St in a locking circuit, as

its energising circuit is interrupted, when the relay W releases. At the contact Ifiw the circuit for the relay WI has been closed which, after operation, closes its contact 23w! preparing a circuit for the relay ZI and XI. These relays however do not operate, as contact 242 is opened. The operation of relay WI also causes as a safeguard, the disconnection of the conversation conductors at the contacts IQwI and wl. At the contact It relay T short circuits the windings I and II of relay W, whereby relay W releases slowly and at the contacts 8t and St the line conductors are switched through, so that the disengaged signal is transmitted to the calling subscriber. By changing over contact III? the signal receiver SE is short circuited, so that it can no longer be affected by the signal frequency contained in the speech. After release of relay W the relay WI also releases, returning its contact 23w! into the normal position.

As soon as the wanted subscriber replies to the ringing current transmitted by the final selector, the relay Z connected to the b-conductor will, when the receiver is lifted operate over its two windings I and II, over the double-contact I'Ic closed at the seizure, normal contact I811, b-conductor and battery in the final selector, applying by its contacts 2L2 and 222 the source of alternating current WQ to the line, whereby a second signal is transmitted over the junction line back to the exchange A, where it gives to the operator a signal from which she can ascertain that the called subscriber has entered into the connection; this is the so-called reply signal which is described in, detail hereafter.

Over the contact 242 closed at the operation of relay Z the relays ZI and Y are energised. The operation of relay ZI is of no significance in this present case. Relay Y breaks, after operation, the circuit of relay Z by the opening of its contact IBy. Relay Z releases, whereby the reply impulse to the exchange A is terminated. Relay Y connects itself into a locking circuit over its own contact, over contact 310 closed at the seizure of the final selector and over the winding of the other relay Z1, serving other purposes which are of no interest here. The subscribers have meanwhile started their conversation.

The reply signal produced in the exchange A by the second signal has been caused by the following switch operations: the relay Y had already been caused to operate by the first, register-disconnecting impulse which arrived over the line VL and had also closed its contact 261/ in the circuit of relay HI, so that this relay was energised over contact 261 and contact 21x. It connected itself in a locking circuit over its contact 28M and the contact 290 of the seizing relay (not shown) which contact was closed at the seizure of the junction line VL and closed preparatorily its contact 3ilhl in the circuit of relay H. If now the relay operates again momentarily by the second impulse which arrives from the source of current WQ over line VL, the circuit for relay H is closed at the contact 31x. Relay H is energised, connects itself over its own contact 32h and the contact 330, closed at the seizure of the junction line VL, in a locking circuit and, by the opening of its contact 34h, breaks the circuit of the end-signal-lamp LS, which switches off. At the setting up of the connection by the operator the lamp had been switchedon over the contact 350, closed at the seizure of the junction line VL, and. over the normal contact 34h; its switching off indicates to the operator that the wanted subscriber has entered into the connection that is to say has answered the call. As may be seen from the operations just described, the device is so constructed that by the first signal arriving from the exchange B, no matter whether it was released in the exchange by the disengaged signal or by the reply of the called subscriber, the disconnection of the register is always effected first and that the reply signal for the operator is only released by the second signal.

When the disengaged signal and the reply of the called subscriber coincide, the signal receiver SE and the relay Z in the repeater Ue operate simultaneously and the following, different switch operations take place: as both operations connect at the contacts 4w, 510, and 2| 2, 22s, the same source of current WQ for the transmission of the signals to the exchange A to the line conductors, only one signal would be transmitted to the exchange A and while the register Rg would be disconnected the signal to the operator would be lost.

In order that this be prevented care is taken that the switch operations started by the disengaged signal and by the reply of the called subscriber are compulsorily separated. Depending on which one of the two devices SE or Ue becomes at first operative at its response to the disengaged signal or to the reply of the called subscriber, in other words, whether the relay W or the relay Z is the first to operate, the reply impulse is stored in the first case that is when the relay W is the first one which operates. If the relay Z operates prior to relay W, the circuit of relay W is interrupted as described below in detail.

If the voice-frequency disengaged signal is the first to operate the relays F, T and W operate in the manner already described with reference to the normal switch operations. Relay W applies by its contacts 420 and 5w the source of a1- ternating current WQ to the conductors of the line, whereby the signal for cutting-out the register is transmitted to the exchange A. Over the contact I6w relay WI operates and interrupts at its contact I9wI and 20w| the conductors of the line between the contacts 411;, Em and 2 I2, 222 and by the switching over of contact 23wI the operation of relay Y and, thereby, the disconnection of relay Z from the line, is prevented. This relay has meanwhile also operated at the lifting of the receiver by the called subscriber and changed over its contacts 2 I z and 222 which, however, on account of the interruption of the line at the contacts Him and 20wI has no effect that is to say no alternating current is transmitted to the exchange A.

However, the second signal to be effected by the operation of relay Z would get lost. In order to prevent this the relay XI in series with relay ZI, when the contact 23wI was changed over, operated over contact 23wI and contact 242,

closed at the operation of relay Z and had closed at the contact 25ml a locking circuit for relay Z extending from earth over winding II of relay Z, the short circuit of winding I, contact I'Ic, I811, 25cm, resistance WiI to battery, earth. The transmission of the reply signal is thus stored by these operations until after release of the relays W and WI and after closing of the contacts 4w, 5w and I Swl, 20wl, the second signal for the reply signal is transmitted over the contacts Hz and 22a which are still changed over, and over the junction line VL to the exchange A. The release period of relay WI determines the length of the pause between the two signals to exchange A. After the switching over of contact 23wI-into its normal position relay Y operates, locking itself over its own contact- 3611 and the contact 310 closed at the seizure, and, at this contact IBy, breaks the locking circuit of relay Z. Relay Z restores with delayed action and switches its contacts Zlz and 22s again over into their normal position. The line conductors are switched through and the subscribers can converse. At the contact 242 the energising circuit of the relays Y and ZI is interrupted. Relay Zl restores, relay Y holds itself over its contact 36y. Relay X had already de-energised, when contact 23wl had been switched to its normal position and had opened its contact 25m in the locking circuit of relay Z.

The case, Where on a coincidence of the disengaged signal and the reply of the called subscriber the receiver is lifted prior to the disengaged signal is still being considered. In this case the signal for the disconnection is, when the relay Z operates, sent out over the line, by connection of the source of alternating current WQ over the contacts Ziz and 222:, just as in the case of the above described normal course of the connection. By the closing of contact 242, the relay ZI operates over contact 242 and the home contact 23w! and in series with relay Zl the relay Y operates. At the contact Zzl the circuit of relay W is broken, so that at the closing of contact If, when eventually the signal receiver SE reacts to speech impulses, the relay W is not energised. After operation of relay Y the circuit of relay Z is interrupted by the opening of contact I811. Relay Z releases and returns its contacts 252 and 222 into their normal positions.

As the disengaged signal is cut off, when the called subscriber replies, the relay F in the signal receiver SE is now caused by the speech of the called subscriber to operate. Relay F closes at its contact If the circuit of relay W, which actuates its contacts. Over the contacts 411) and w the source of alternating current WQ is again applied to the conductors of the line whereby the second signal, notifying the operator of the reply of the called subscriber, is sent out. Relay F switches the line conductors through and shortcirouits the signal receiver, so that it is not affected by the conversation of the subscribers who are now in a position to communicate with each other. In this case, the release period of relay Zl determines the length of the pause between the two signals to the exchange A.

I claim: I

1. In a telephone or like system, a trunk line, two devices associated with one end of said trunk line, said devices operable in succession at times and simultaneously at other times, and means controlled by said devices for transmitting an impulse over said trunk line responsive to the operation of each device if they are operated in succession and for transmitting two impulses in succession over said trunk line if said devices are operated simultaneously.

2. In combination with two devices adapted to be operated simultaneously at times and in succession at other times, means controlled by said devices for transmitting an impulse of current responsive to the operation of each device if they are operated in succession and for transmitting two impulses of current in succession if said devices are operated simultaneously.

3. In combination, a line, means responsive to transitory impulses for repeating said impulses over said line, means responsive to other transitory impulses for repeating said other impulses over said line, each of said means normally operating independently of the other of said means to repeat each impulse received thereby in a substantially fixed time relationship to the receiving of that impulse, and means controlled by said two means if said first means is repeating an impulse over said line at a time when second means receives one of said other transitory impulses for delaying the repeating of the impulse received by said second means until said repeating of the impulse by said first means has been finished.

4. In combination, a line, means responsive to transitory impulses for repeating said impulses over said line, means responsive to other transitory impulses for repeating said other impulses over said line, each of said means normally operating independently of the other of said means to repeat each impulse received thereby in a substantially fixed time relationship to the receiving of that impulse, and means controlled by said two means for storing an impulse received by one of said means if, at the time same isreceived, said other means is repeating an impulse over said line.

5. In combination, a line, means responsive to transitory impulses for repeating said impulses over said line, means responsive to other transitory impulses for repeating said other impulses over said line, each of said means normally operating independently of the other of said means to repeat each impulse received thereby in a substantially fixed time relationship to the receiving of that impulse, and means controlled by said two means for causing each impulse repeated over said line by said first means to be separated by a predetermined minimum interval of time from each impulse repeated over said line by said second means.

6. In combination, a line, means operated by impulses and normally effective upon each operation to transmit an impulse over said line substantially at once, means operated by other impulses and, upon each operation, normally effective substantially at once to transmit over said line an impulse substantially identical in character to the impulses transmitted thereover by said first means, and means controlled conjointly by said first two means for causing each impulse transmitted over said line by one of said first two means to be separated by a predetermined minimum interval of time from each impulse transmitted over said line by the other of said first two means.

7. In combination, a receiving circuit and a transmitting circuit, means responsive to each impulse of direct current received over said receiving circuit and normally efiective to transmit an impulse over said transmitting circuit substantially at once, means responsive to each impulse of voice frequency current received over said receiving circuit and normally efiective substantially at once to transmit over said transmitting circuit an impulse substantially identical in character to the impulses transmitted thereover by said first means, and means controlled conjointly by said first two means for causing each impulse transmitted over said transmitting circuit by said first means to be separated by a predetermined minimum interval of time from each impulse transmitted thereover by said second means.

8. In combination, a line, a source of current,

two circuits over which said source may be connected to said line, means operated by impulses and effective upon each operation to transitorily close a contact in the first of said circuits thereby to connect said source to said line, means controlled by said first means, when operated, to open a contact in said second circuit and to maintain said contact open for a predetermined interval after said contact in the first circuit has been re-opened by said first means, means operated by other impulses and effective upon each operation to close a contact in said second circuit thereby normally to connect said source to said line if the first-mentioned contact in said second circuit has not been opened, and means effective if said last contact is closed at a time when the first mentioned contact in said second circuit is open for maintaining said last contact closed for a predetermined interval after the reclosure of the first mentioned contact in said second clrcuit.

9. In combination, means for receiving impulses, a device at normal, means controlled by said first means for operating said device for a predetermined interval of time responsive to the reception of an impulse by said first means and for then restoring said device to normal, other means for receiving impulses normally effective to repeat each impulse received thereby substantially at once, and means controlled by said device, whenever said last means receives an impulse while said device is operated, to delay the repeating of that impulse until said device has restored to normal.

ALOIS BRANDSTEI'I'ER. 

